+1 for Katamari, it was one of the options I considered for my next game, but decided on something else. 3D golf is a glearing gap, but a gap that many others would no doubt have seen.

Quote:Keep in mind though that adding your game to the AppStore takes a long time...

For a competitive game it's going to take at least a couple of months to create, so you never know what the competition will be by then anyway. At this stage your safest bet might be to chose something that hasn't been done before and would fill a gap in any gaming market other than the iPhone. My guess would be that in 2 months time you will be not only competing with thousands more games, but most of them will be exactly the most obvious missing games right now.